Fungi are becoming increasingly utilized for production of numerous commercially useful products. A type of fungi known as “filamentous” fungi are currently used for the industrial scale production of metabolites such as antibiotics (penicillins and cephalosporins, for example) and organic acids (citric and fumaric acids for example). Filamentous fungi are additionally useful for the industrial production of enzymes such as, for example, proteases and lipases.
Utilization of a filamentous fungus species for production of desired compounds often involves growing submerged cultures of the fungus. Filamentous fungi can exhibit numerous morphologies in submerged cultures, one of which is the filamentous morphology. When fungi in culture exhibit a filamentous morphology, the filamentous growth can increase the viscosity of the culture medium. The increased viscosity can affect the mass transfer and aeration properties of the culture, can cause mixing problems in a bioreactor, and can typically be accompanied by decreased productivity.
Alternatively, “filamentous” fungi can exhibit a pellet morphology. In contrast to cultures of fungi exhibiting a filamentous morphology, the viscosity of cultures of fungi exhibiting a pellet morphology can be relatively low and can utilize less power for mixing and aeration of the culture. For many products, for example citric acid, itaconic acid, statins, penicillins, and various enzymes, productivity can be enhanced utilizing fungus exhibiting a pellet morphology relative to fungus exhibiting a filamentous morphology. However, at least in certain fungal species, production of peptic enzyme or fumaric acid, for example, can be enhanced by utilizing a fungus exhibiting a filamentous morphology.
It would be desirable to develop methods to promote a desired morphology in a fungus and to develop methods for influencing or controlling morphologies exhibited by a fungus in a culture to optimize productivity.